This invention relates to bicycles.
The most common type of bicycle has a one-piece frame connected to the front and rear wheels, the frame including a seat-supporting tube which receives a shaft that holds the seat at an adjustable height. It has been recognized that the rider can be better isolated from road shocks by utilizing a two-piece frame which includes a front frame coupled to the front wheel, a rear frame coupled to the rear wheel and pivotally connected to the front frame, and a shock absorber which urges the frames towards a normal position but which allows them to pivot with respect to each other to absorb a shock. The design of a simple and effective bicycle of the latter type has been hampered by difficulty in the placement of the shock absorber that couples the front and rear frames. Thus, for example, U.S. Pat. No. 644,957 utilizes a shock absorbing spring that lies in an upper tubular frame member and which extends through a special slot in the feed shaft, to accommodate the shock absorber while still permitting slideable adjustment of the seat shaft. U.S. Pat. No. 644,787 eliminates the need for a complicated mechanism extending through the seat shaft by locating the entire shock absorber behind the seat-supporting tube, but only a short shock absorber can be used. Italian Pat. No. 425,968 shows a bicycle with shock absorbers lying on either side of the seat-supporting tube, but this requires two shock absorbers that are laterally spaced. A relatively simple bicycle of the type utilizing two pivotally connected frames, but which employed a single long shock absorber mounted for maximum shock absorption and in a manner that provided minimum interference with normal riding of the bicycle, would permit an economical bicycle to be provided for riding over rough terrain.